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Thread: Pressure testing a watch

  1. #1

    Pressure testing a watch

    Does anyone know somewhere in the Somerset/Bristol area that can pressure test my Doxa and the sort of cost involved?

    Also, why exactly is involved when it's done? I assume they use pressurised air in some kind of sensitive chamber but I how can they tell at what point the watch's seals are not holding the pressure? And can it damage them? :shock:

    Cheers

  2. #2
    Grand Master magirus's Avatar
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    Re: Pressure testing a watch

    I recently had my CWC diver in to Duncan Potter at Genesis to have a couple of things attended to, and a pressure test was included. The whole job was very reasonable, so I would think a test alone wouldn't cost much. He's very quick to respond to emails, and the turnaround time was quick too. Of course all the better if you can find someone local and call in person.
    viewtopic.php?f=10&t=203722
    F.T.F.A.

  3. #3

    Re: Pressure testing a watch

    The air chamber test you describe is not a full pressure test, but it will give you a decent idea of how the seals are holding up. It uses a micrometer to measure deflection of the crystal under vacuum and moderate positive pressure (around 10 bar), and has the advantage of being fast and non-invasive. A proper test involves uncasing the movement and dial, applying and holding the full rated pressure hydrostatically, then checking for water ingress.

  4. #4
    Craftsman
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    Re: Pressure testing a watch

    Quote Originally Posted by Belligero
    The air chamber test you describe is not a full pressure test, but it will give you a decent idea of how the seals are holding up. It uses a micrometer to measure deflection of the crystal under vacuum and moderate positive pressure (around 10 bar), and has the advantage of being fast and non-invasive. A proper test involves uncasing the movement and dial, applying and holding the full rated pressure hydrostatically, then checking for water ingress.
    Apologies if this is a stupid question, but why do you need to uncase the movement and dial? :?

  5. #5
    Master
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    Re: Pressure testing a watch

    Normally around 5-10 quid mark there is somewhere on the net a guide to make your own, but i never could be bothered. :)

  6. #6

    Re: Pressure testing a watch

    Quote Originally Posted by cad monkey
    Apologies if this is a stupid question, but why do you need to uncase the movement and dial? :?
    I suppose you don't strictly have to, but you might regret it if the case happens to fail the test.

  7. #7
    Craftsman
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    Re: Pressure testing a watch

    Quote Originally Posted by Belligero
    Quote Originally Posted by cad monkey
    Apologies if this is a stupid question, but why do you need to uncase the movement and dial? :?
    I suppose you don't strictly have to, but you might regret it if the case happens to fail the test.
    Again this is probably a stupid question but wouldn't you be left with a hole at the crown?

  8. #8

    Re: Pressure testing a watch

    Hydrostatic testing is a "wet" procedure and uses positive pressure, so you'd be left with a flooded watch.

    I'll have to get a few photos of the local 1960s Sea-Dweller pressure-testing apparatus; it's quite the piece of memorabilia, though still perfectly functional.

  9. #9
    Master lysanderxiii's Avatar
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    Re: Pressure testing a watch

    Quote Originally Posted by Belligero
    The air chamber test you describe is not a full pressure test, but it will give you a decent idea of how the seals are holding up. It uses a micrometer to measure deflection of the crystal under vacuum and moderate positive pressure (around 10 bar), and has the advantage of being fast and non-invasive. A proper test involves uncasing the movement and dial, applying and holding the full rated pressure hydrostatically, then checking for water ingress.
    That kinda defeats the purpose of checking to see if the gaskets are in right and good, doesn't it?

    What you have described is a qualification test. Done one long before the watch is put into production to see if the case design will, in fact hold the designed pressure. Once it passes, there is no point in doing it again unless your supplier of steel, crystals or gaskets, etc. changes.

    After the watch is assembled there needs to be a quality check on the gaskets, seals, etc. This is done with the movement in place.

    The high pressure air test at 10 atm is usually fine. If the watch holds 10 atm (150 psi) the gasket and seals were installed correctly, and if the correct gaskets and seals were used, it should be good to it rated pressure.

    This method offers the fewest risks as the watch cannot get wet.

    After you do the air test, you could put the watch in a high pressure water tester and go all the way to 30 atm or 125 atm or whatever the watch is supposed to stand...

    Oh, and if the watch leaks you usually don't get a flooded watch you get one that is moist inside. Once the seal fails, the pressure drops almost instantly, if you back off immediately, very little water will actually get in (unless it is a cristal failure or somthing massive).

  10. #10
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    Re: Pressure testing a watch

    Sit on it and fart.
    Quickly put the escape valve under the flame of a lighter.
    Be carefull with acryllics.

  11. #11

    Pressure testing a watch

    Timpsons in Bath did mine for a tenner.
    "Bite my shiny metal ass."
    - Bender Bending Rodríguez

  12. #12

    Re: Pressure testing a watch

    Quote Originally Posted by lysanderxiii
    What you have described is a qualification test.[...]Once the seal fails, the pressure drops almost instantly, if you back off immediately, very little water will actually get in (unless it is a cristal failure or somthing massive).
    I'll have to check on the uncasing part, but I'm certain that - at least on Sea-Dwellers - the watch undergoes a lengthy hydrostatic pressure test in addition to the dry test during a full service. A common tool for doing this is the Roxer Natator, described here: http://www.watchrestoration.com/roxer125.html. Some repair centres also have a testing machine for DSSDs, which is obviously a bit over-the-top. The ones that don't have to send them away to a facility that can test to full pressure for a valid authorized service.

    I will ask about the exact procedure next time I speak with the watchmaker; I'm interested as well.

  13. #13
    Master lysanderxiii's Avatar
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    Re: Pressure testing a watch

    Quote Originally Posted by Belligero
    Quote Originally Posted by lysanderxiii
    What you have described is a qualification test.[...]Once the seal fails, the pressure drops almost instantly, if you back off immediately, very little water will actually get in (unless it is a cristal failure or somthing massive).
    I'll have to check on the uncasing part, but I'm certain that - at least on Sea-Dwellers - the watch undergoes a lengthy hydrostatic pressure test in addition to the dry test during a full service. A common tool for doing this is the Roxer Natator, described here: http://www.watchrestoration.com/roxer125.html. Some repair centres also have a testing machine for DSSDs, which is obviously a bit over-the-top. The ones that don't have to send them away to a facility that can test to full pressure for a valid authorized service.

    I will ask about the exact procedure next time I speak with the watchmaker; I'm interested as well.
    Rolex?

    They might re-qual the case every time, but 1) They are a parnoid bunch (reputation and all) and 2) have to justify that price tag on the service....

    If you replace the crystal, you might want to test without the movement, it's easier to get some of them in wrong and have them leak. But, in 99% of the cases, an air test is fine...

  14. #14

    Re: Pressure testing a watch

    Quote Originally Posted by lysanderxiii
    [...]They might re-qual the case every time, but 1) They are a parnoid bunch (reputation and all) and 2) have to justify that price tag on the service....

    If you replace the crystal, you might want to test without the movement, it's easier to get some of them in wrong and have them leak. But, in 99% of the cases, an air test is fine...
    Agreed completely; I'm quite satisfied with a good air test, myself.

    I must say that the '60s COMEX-developed Rolex pressure tester is quite the piece of steel and acrylic, and I appreciate how it hearkens back to the day when a diver's watch was used as a tool by professionals. I'll have to get a photo of it, even just as a reply to the "is it OK to wear my Submariner in the shower?"-type of questions. Mercifully, TZ-UK seems to have a lot fewer of those than certain other forums.

  15. #15
    Grand Master
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    Re: Pressure testing a watch

    I use a wet tester which I bought recently from China.

    Basically, the watch is suspended in air which is pressurised to a set figure (6 bar max on mine). After a few minutes the pressure is dropped slightly and the watch immersed in water. If the watch isn`t watertight, air will have entered the case and will be seen escaping as the pressure is dropped further. This also has the benefit of showing where the leak is because the stream of tiny bubbles is easy to see. Watches with large bezels can be misleading because air gets trapped under the bezel; this also happens around the crown on some watches and it is possible to misinterpret this as air leaving the case.

    A simple procedure in principle, but these things have to be used v. carefully to avoid ingress of water or potentially pressurising the case and blowing the glass out! I`ve put a fair amount of thought into using mine and I could almost write a book on the potential drawbacks if used carelessly. It is very unwise to take a watch and simply crank the pressure straight up to the maximum; I always test them in stages which takes longer but is safer.

    As for taking the movement out, I`ve never heard of this being done. However, if I've dismantled a watch for servicing I will replace the glass, caseback and crown then test the watch without its movement. This will show whether there is a major problem anywhere and is good practice IMO. I always retest the watch after final assembly too.

    Paul

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